DIY Bookshelf Speakers With MarkAudio CHN-50 Drivers

Intrigued by the potential sonic advantages of a full-range driver, and spotting the introduction of a new kit by Asian driver manufacturer MarkAudio, I decided it was time to give one a try. This coincided with the arrival of an Up2Stream AMP review sample, presenting a need for a small, easy to drive loudspeaker to pair with it.

Finished Speakers Front:top View

The sample is not of the official ToziOne kit from Markaudio, but a custom box using the CHN-50 driver. UK distributor KJF Audio not only provided the drivers and lining material for this project but were also immensely helpful in providing a sketch for a suitable enclosure. KJF also offer a full range of speaker kits and parts for any project. My thanks go out to Stefan for helping to make this series a reality. The provided diagram is offered below with credit to Scott Lindgren of Woden Design who offer a range of plans for different speakers.

Chn50 Vented Box Metric

Our enclosure is a simple ported design with 12 mm construction material specified. I used 12 mm MDF and finished the boxes in a light oak veneer with black cloth grills in plywood. I had initially tried a plywood box but the boards were cupped, resulting in poorly fitting joints and uneven faces which proved nigh-on impossible to sand flat.

The original plan was to integrate the Up2Stream amp board into one of the boxes, but I decided to take a different approach. Typical active speakers are limited in that only their internal amplification can be used, and the channel containing the amplification, and thus the connectors and controls cannot be reassigned. I decided to build these as ordinary boxes, and keep the amplification external; likely contained within a plinth, but we’ll explore this in an upcoming article.

Raw Boxes Fronts Cut

Not only does this avoid any sonic compromise from the minimal difference in volume taken up by the electronics, but it allows greater flexibility as though designed to work together, the speakers and amplifier can be separated if desired. I also wanted to hear what the Markaudio drivers would sound like in the context of our reference system, which would not be possible – or at least easy – were they designed as a purely active system.

One of the key considerations in speaker building is ensuring air-tight joins between cabinet panels. Arguably the best methods are a 45-degree mitre or rebated panels, which if cut accurately will both produce an extremely solid, airtight cabinet. The box drawings supplied, however, were of a simple edge-to-edge construction, in which the front and rear panels overlapped the sides, top and base. This is still a perfectly acceptable means of construction and is how I chose to build these boxes. The glue and the application of veneer will eliminate any gaps.

Raw Boxes Rear With Vents Fitted

The boxes were glued with a generous application of PVA wood glue and nailed evenly with an air nailer, which held the panels securely while the glue dried and kept everything in place. The cabinets were then flat sanded on their outer surfaces before veneer application, which is especially critical with an iron-on veneer. Driver (65 mm) and port (34.5 mm) holes were drilled before construction, as were the 10 x 3 mm grill magnet recesses on the front panels. The port is a 108 mm length of 35 mm plastic pipe, its hole cut as an interference fit and glued into place for further strength.

The top, back and a single side of each cabinet is lined with a 12 mm damping material, installed prior to installing the front panel. So too were the gold-plated speaker terminals, configured in single-wire mode. As these are full-range drivers there is no crossover required. I simply bolted the terminals to some acrylic terminal plates, bolted this securely to the rear of each speaker after cutting a slot through which the terminals could protrude, and installed a simple wire pair for the driver.

Raw Box Front Fitted

I used some left-over gasket foam supplied with the drivers for the terminal plates, maintaining the airtight seal. Given the small driver hole, the terminals are all but inaccessible when the front panel is in place, so I made doubly sure they were secured before glueing and nailing the fronts.

Front View Of Inside Boxes Vents Fitted

Sanding complete, I proceeded to veneering. I chose a pre-glued, iron-on veneer which is the easy option. A traditional veneer is vastly superior though is more challenging and time-consuming to apply. Iron-on veneers are an acceptable compromise between quality and convenience providing you pick a decent product. I didn’t, and there were patches where the veneer chipped and pealed during the final finish. It does have a nice texture to the grain, however, and careful application of a general-purpose wood filler smoothed out any imperfections.

Veneer Fitted And Rear Connectors Going On

I trimmed the veneer slightly oversized with a Stanley knife, ironed it to each panel keeping the grain as straight as possible, and trimmed as much of the excess as possible with the knife. I finished up each edge by sanding flush with the panel.

Finished Speakers Side View

Veneer in place, I sanded to 320-grit to remove any excess glue especially from the edges, where I had rolled the iron to give a smooth, uniform edge. Sanding complete, a couple of coats of French polish was applied and left to dry, before a coat of furniture wax applied and machine buffed to the final finish.

The drivers include pre-cut gaskets which were adhered to the front panel before the drivers were slotted into place and screwed with the included fasteners.

Rear Of Grill With Magnets

This was my first attempt at covering a speaker grill. I chose to use a stapler as opposed to adhesive, though would almost certainly choose a spray-on contact adhesive next time around. I am however pleased with how these came out, my only real challenge being wrapping the corners. I could have done a neater job cutting the excess, but these are satisfactory for a first attempt. They’re secured using 10 mm neodymium magnets, 1 mm in thickness in the front panels and 3 mm thickness in the grills. The pull force is just great enough to secure the grills in position, though with hindsight I would’ve installed the thicker magnets in the speaker fronts too.

Finished Speakers Rear View

And the sound? It’s lively and dynamic, with the staging and coherence one would expect from a full-range driver. It’s very much like a planar-magnetic speaker in that regard, though with dynamics, scale and power more akin to a traditional box.

I had concerns as regards the top end in a system where the driver is responsible for the full frequency range. These concerns were unfounded, as the top end is brimming with detail. Vocals, in particular are delightful. Bass is surprisingly good too. It won’t shake the walls but it’ll get surprisingly deep and is full and well defined. A sub could fill out the bottom end a little, but it’s by no means essential.

Finished Front View Grills Off

I’m hugely impressed by the CHN-50, and by extension the concept of the full-range driver. Look out for a future build featuring larger MarkAudio drivers, likely Alpair 10 or 12s in a floorstanding enclosure. I have quite a few DIY projects coming this year and look forward to your comments below.

By Ashley

I founded Audio Appraisal a few years ago and continue to regularly update it with fresh content. An avid vinyl collector and coffee addict, I can often be found at a workbench tinkering with a faulty electronic device, tweaking a turntable to extract the last bit of detail from those tiny grooves in the plastic stuff, or relaxing in front of the hi-fi with a good album. A musician, occasional producer and sound engineer, other hobbies include software programming, web development, long walks and occasional DIY. Follow @ashleycox2

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